A high plasma free DNA concentration requires a definitive diagnosis in conjunction with medical history and other tests. Plasma free DNA refers to the DNA in the blood that is free from the cells, mainly from the DNA released by the disintegration of leukocytes, the DNA released into the blood from necrotic tissues, especially tumor tissues, and the DNA from infected viruses and bacteria. Plasma free DNA can be of value as a diagnostic biomarker for acute coronary syndromes, as an adjunct to diagnosis of deep vein thrombosis in elderly patients with bone fractures, and ovarian cancer, but by itself is not a definitive diagnosis of disease. When the plasma free DNA concentration is high, it is necessary to go to the hospital in a timely manner, complete the relevant clinical examination, and carry out targeted treatment after clarifying the cause of the disease.